Thomas a



(No Model.)

- T. A. EDISON.

ELEGTRO MAGNETIG- MOTOR. No. 251,541. Patented Dec. 211881..

UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF MENLO PARK, NEW JERSEY, ASSIGNOR TO THE EDISONELECTRIC LIGHT COMPANY, OF NEW YORK, N. Y.

ELECTRO-MAGNETIC MOTOR.

SPECIFICATION forming part of Letters Patent No. 251,541, dated December27, 1881.

Application filed May 31, 1881. (No model.)

To all whom it may concern:

Be it known that I, THOMAS A. EDisoN, of Menlo Park, in the county ofMiddlesex and State of New Jersey,have invented a new and usefulImprovement in Electro-Magnetic Motors; and I do hereby-declare that thefollowing is a full and exact description of thesame, reference beingbad to the accompanying drawing, and to the letters of reference markedthereon.

The object I have in view is an improvement in electro-magnetic motorsfor driving light n1acl1inerysuch as sewingniachines, lathes, 850., butespecially designed for sewing-machineswhich improvement will enable thespeed of the motor to be readily regulated, so that the driven machinecan be run fast or slow, as desired, without breaking circuit, and sothat in starting or stopping the motor the resistance of its circuitwill be regulated in order to prevent any noticeable effect upon theelectric lamps in the system, the motor and lamps being worked upon thesame conductors.

This I accomplish by including in the motor-' circuit an adjustableresistance and a lever, operated preferably by avfoot-treadle, suchdevices enabling the operator to throw resistance into and out of thecircuit by the movement of the foot-treadle, and thereby to run thedriven machine at a slower or faster speed. The lever is also adapted tostand normally so that upon closing circuit all the resistance will bethrown in, and the necessary degree of magnetization will be attainedbefore any resistance will be thrown out, so that as the wire resistanceis thrown outthe motor will increase in speed and give a counterelectromotive force in its own derived circuit and compensate for thelessening of actual wire resistance. In this way a nearly constantresistance will be maintained and lamps connected with the same mainconductors will not be appreciably affected. A suitable switchconveniently located is provided for making and breaking circuit.

In the drawing a sewing-machine is represented in end elevation with myimprovement attached thereto.

Ais the frame of a sewing or other light machine, and B is the motormounted thereon and driven by the circuit 1 2, derived from the mainconductors of the system. 0 is the Wire resistance, and D is a leverpivoted to the frame A, through which resistance and lever the circuit 12 passes. Thisleveris drawn in one direction, so as to throw all theresistance into the circuit by a spring, E, and it is connected by arod, a, with a foot-trcadle, F. G is the switch for making and breakingthe circuit.

What I claim is- 1. The combination, with an electric motor, of aresistance, a lever included in the motorcircuit and adapted to beoperated by hand or foot for throwing the resistance in or out ofcircuit, and means for normally holding the lever at the point to throwin the maximum resistance, substantially as described.

2. The combination, with the electric motor,

of the resistance, the lever, the retractingspring, the foot-treadle,and switch, substantially as set forth.

This specification signed and witnessed this 20th day of May, 1881.

, THOMAS A. EDISON. Witnesses:

B10111). N. DYER, H. W. SEELY.

